A navigation system is a system for providing information for traveling of vehicles using satellites and is also called an autonomous navigation system.
The navigation system receives predetermined data from global positioning system (GPS) satellites using a GPS receiver and calculates a position thereof on the basis of the received data.
The navigation system can provide information that aids in driving, such as informing a user of the current location of a vehicle on the basis of the position information thereof, routing a route to a desired destination, and guiding the user on the route.
The navigation system stores geometry data about maps and point-of-interest (POI) information indicating buildings, roads, and the like on the maps and uses the stored geometry information and the POI information as information for route guidance.
That is, the navigation system receives signals including latitude and longitude information from GPS satellites, calculates the location of a user, outputs the calculated location, and provides a route to a desired destination of the user while map-matching POI information to geometry information arranged according to latitude and longitude.
With a recent increase in the number of vehicles, the number of intersections having a plurality of access roads increases since roads have become widened or additional roads are built. When such an intersection is present on a route, the navigation system indicates information about an exit direction and an entry direction of the intersection as an image on geometry information and provides voice guidance about the entry direction on the basis of a distance.
However, conventional voice route guidance is performed at a predetermined interval or predetermined frequency irrespective of user requirements. Accordingly, some users recognize that route guidance is excessively frequently executed which may disturb safe driving, while other users recognize that route guidance is too infrequently executed and thus they may miss necessary guidance.